1. Technical Field
This technology pertains generally to imaging, and more particularly to phase contrast imaging for cell screening.
2. Background Discussion
Flow cytometry is a powerful tool for cell counting and biomarker detection in biotechnology and medicine, especially with regards to blood analysis. Standard flow cytometers perform cell type classification both by estimating size and granularity of cells using forward- and side-scattered light signals and through the collection of emission spectra of fluorescently-labeled cells. However, cell surface labeling as a means of marking cells is often undesirable, as many reagents negatively impact cellular viability or provide activating/inhibitory signals, which can alter the behavior of the desired cellular subtypes for downstream applications or analysis.
Cell protein content measurement can be used in many biomedical applications such as blood doping detection, infection monitoring, drug development and screening, studies of necrosis and apoptosis, cell cycle progression and differentiation, and in cancer diagnostics. Current methods for cell protein concentration measurement include electrical methods based on dielectrophoresis, mechanical methods based on microchannel cantilevers, and optical methods based on scattering patterns, emission spectra of external cavity lasers, and holographic and phase microscopy. These methods are either inherently too slow for high-speed flow cytometry applications, or require feedback mechanisms to provide necessary precision.
Furthermore, size-based classification can also be used for label-free identification of cells of interest in a suspension stream. However, due to significant overlap of size ranges between most mammalian cells, size-based technologies require additional layers of parametric gating to be useful as a diagnostic tool.